The shooting occurred around 6 a.m. at Park Place Apartments at 804 Kendall Drive, on the city's east side.
According to Durham police, the children's parents are estranged. The children had spent the weekend with their father at his Kendall Drive home.
Police say the mother called to ask about picking up the kids, and the boy told her he had been beaten and that his sister was bleeding. The mother rushed over and found her two children shot in an upstairs bedroom.
The girl, Brianna Crutchfield, died, and the boy, Ricardo Crutchfield Jr., is in fair condition at Duke Medical Center. He underwent surgery Monday afternoon.
Police canine units were brought in, and the father, Ricardo Crutchfield Sr., was found an hour later in a crawl space under the apartment unit shot twice in the chest.
He told police he was a crime victim. He is in serious condition at Durham Regional Hospital.
Police say the neighborhood is very quiet and that they've never had any calls. Nor were there any previous domestic violence reports at that address.
Neighbor Charles Pickett said he is very astonished by the crimes, that the neighborhood has been very quiet.
"I had a false sense of security, that everything is fine and it won't happen here, or towards me. But I feel totally different. Because nothing like this has ever happened here. This is a very quiet neighborhood. This is so tranquil, you never think it could happen. But it does. My guard is up now," Pickett said.
Police removed a large amount of evidence from the apartment. Police are not ruling the father out as a suspect.
Police say the two people they need to talk to the most, the father and the son, have been unable to speak to them yet because of the injuries they received. Police hope to be able talk with them Tuesday.
Relatives say Crutchfield is a very loving father, and despite the separation, he never raised his hand against the children.
The children attendedLittle River Elementary School. Some crisis teams will be on hand there Tuesday.